After Windsor Castle caught fire and the private affairs of her children were luridly exposed in the media, the Queen spoke of her annus horribilis.

The dreadful year of 1992 seems a period of tranquillity, however, in comparison with a year of events that befell the man who was proclaimed king 500 years ago this month.

A new history suggests that 1536 turned Henry VIII from a gifted, handsome and companionable king into the fat, wife-killing tyrant of popular imagination.

Suzannah Lipscomb, a doctoral student at Balliol College, Oxford, and research curator at Hampton Court Palace, arrived at this conclusion while preparing an exhibition on Henry VIII to mark the quincentenary of his arrival on the throne.

“Looking at the events of Henry’s life, I had never noticed that so many of them coalesced in a single year. There was a considerable difference in the King before and after,” she said. “No one had written this before.”

In 12 months Henry suffered a riding accident, an alleged cuckolding, the death of his beloved illegitimate son and a rebellion. As he turned 45, then regarded as the beginning of old age, these separate traumas accumulated into a midlife crisis from which he never recovered.

When Henry was proclaimed King on April 22, 1509, contemporaries lauded his wit, wisdom and athleticism. Two decades later, in 1529, the Dutch scholar Erasmus described him as “a man of gentle friendliness . . . more like a companion than a king”.

Ms Lipscomb argues that Henry was still the good-humoured monarch at the beginning of 1536. He rejoiced in his marriage to Anne Boleyn, who had already produced a healthy girl and was three months pregnant.

He was also still a fine figure of a man, when on January 24, 1536, charging at full gallop in the tiltyard, he was knocked from his horse by an opponent and lay unconscious for two hours. The fall appears to have burst an ulcer on his thigh: the recurring pain in his leg bred an irritability that occasionally exploded into intense, murderous grumpiness. It curtailed his sporting career and he grew fat.

Anne Boleyn claimed that the shock of that fall caused her to miscarry. She had failed to produce a son for the King, and rumours began to circulate of her adultery with four men, among them her own brother and one of Henry’s closest friends.

Ms Lipscomb believes that Anne was innocent of the charges but that Henry became convinced that they were true. This conviction “upended his world”.

In the subsequent trials, Anne was accused of having ridiculed the King, saying that he was “not skilful in copulating with a woman, and he had neither virtue nor potency”. Such ridicule brought into question his ability to rule a kingdom, and in October his “potency” was openly challenged when, in the North, 50,000 men rose in the Pilgrimage of Grace, a rebellion against the Reformation, high taxation and the dissolution of the smaller monasteries.

Henry blustered, but his own army numbered only 9,000 men, and he was forced into a temporary but humiliating accommodation with the rebels.

Ms Lipscomb argues that his rapid marriage to Jane Seymour, his depiction as a vigorous hero by the artist Hans Holbein, his policies on religion and his increasing brutality were reactions to the events of that bruising year, and were attempts to project himself as a virile, reforming King.

The Tudor historian Dr David Starkey said that Ms Lipscomb’s book, 1536, represented “a bold and original attempt to unravel . . . how, when and why Henry VIII changes from a handsome Prince Charming into a fat and loathsome Bluebeard”.

Dr Starkey was not “fully convinced” by her argument, however. He told The Times: “Henry certainly undergoes a transformation. But I would put it significantly earlier.”

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